Ecological factors affecting the diel activity of rodents in a sedgeland habitat within Białowieża Primeval Forest were examined by live trapping. The results of a short-term but intensive trapping scheme, with checks every 3 hours, confirmed known differences in activity patterns between voles and mice. We observed an even distribution of vole activity around the 24-h cycle, rather than a marked preference for nocturnal activity in summer. Ten-year data from trapping of the same rodent assemblage dominated by Microtus oeconomus showed that an increase in population density of the dominant species resulted in more diurnal activity of those voles and the co-occurring bank voles. This shift of activity seemed to result from social tensions in a crowded habitat that mostly affected young root voles, as well as individuals of subordinated species. On the other hand, increased predation pressure exerted by weasels Mustela nivalis encouraged more nocturnal activity of voles. The shift was either a direct response of local prey to increased activity of the local diurnal predator, or the ancient anti-predatory response of mammals seeking safety in darkness.

Crabapple Island (located in Bełdany Lake, NE Poland) was the site of concurrent study on the reproduction and survival of bank voles (Myodes glareolus) and yellownecked mice (Apodemus flavicollis) in 1994–2002. We evaluated the importance of reproduction and survival for seasonal population dynamics as well as the formation of a summer peak in population numbers. Yellow-necked mice started breeding earlier in the spring than did bank voles. However, early breeding and rapid increase in numbers of both species resulted in a particular seasonal distribution of pregnant female numbers indicative for delayed (even up to 40 days) maximum reproduction of yellow-necked mice as compared with that of bank voles. A high survival rate of mature females of the yellow-necked mouse preceeds the July peak in population numbers, and a low survival rate of immature individuals of this species contributes to a rapid decline of numbers following this peak. The survival rate of mature females of the bank vole does not affect the summer peak in population numbers of this species. A relatively high survival rate of immature individuals of bank voles following the summer peak results in a slow decrease of its population size.

The sex-related spatial genetic structure of a free-living population of the common vole (Microtus arvalis) was assessed using sequence and haplotype frequency data of the complete mitochondrial cytb gene in three seasons. Six haplotypes were resolved, three of them (A, B and C) were shared among seasons and sexes. The remaining three singletons did not match any of the local females. Pairwise tests did not show significant differences in haplotype frequencies between seasons. However, we observed such differences between the sexes. The aggregation index calculated for haplotype B showed a clumped female spatial distribution and revealed two clusters of the matrilineal lineage in the population. The female effective population size (N_ef) estimated from shifts of haplotype frequencies between seasonal samples was quite small and the N_ef/N_f ratio ranged from 0.18 to 0.35. We suggest that both factors, low N_ef and female philopatry may be responsible for considerable inter-population differentiation previously reported in this abundant vole species.

The long-term dynamics of small mammal communities inhabiting a mosaic of agricultural and forest habitats, that is, mixed forest, lakeside alderwood forest and arable land, set aside in the second period of the study, was analysed. No cyclicity was recorded in the numbers of the dominating species, that is, the bank vole (Myodes glareolus) and the yellow-necked mouse (Apodemus flavicollis). Fallowing of the arable land resulted in a decline in diversity and species richness of small mammals in the habitat mosaic under study. The greatest changes were recorded in the community inhabiting a narrow belt of spatially heterogeneous alderwood along the lakeshore. In this community, a considerable increase in the number of yellow-necked mice and a general increase in the dominance of forest species took place. We suggest that the fallowing of extensive arable lands, taking place in Poland for the last two decades, constitute an attractive source of food for small mammals and may lead to a considerable decline in small mammal species diversity within the landscape or even cause local extinctions in some species.

We conducted visual surveys of the red squirrel Sciurus vulgaris in 2005 in 11 parks and city forests of Warsaw with particular focus on the population in Łazienki Park in the city center. We found a significant association between the size of the park and the number of observed red squirrels, with the highest number occurring in Łazienki Park. In this park, the abundance index of the population in 2005 was 1.8 individuals per ha, which was three times higher than in 1956 and 1986, when similar surveys were carried out. The number of red squirrels observed in Łazienki Park was influenced by season, temperature, air humidity and tree species, the seeds of which are a potential food source for red squirrels.

A three-year (2004–2006) study on a 1-km road section near Warsaw (central Poland) indicated that road traffic may be an important cause of mortality in bats, at least locally. The total number of bat casualties was 52, mostly recorded on a short subsection (up to 9 individuals per 100 m of roadway and year). The bats were killed near two linear landscape elements — tree lanes, during the migration to mating and hibernation roosts. Myotis nottereri dominated the sample of dead individuals (over 70%).

In order to estimate small mammal diversity in Warsaw we analysed pellets of tawny owls inhabiting green areas. Altogether we found 21 species of mammals (9 species in the city centre and 19 on the outskirts). In the central zone the largest share was comprised of striped field mouse, house mouse and rats, while species connected to forest and open areas dominated in the outskirts.

Spatial organisation, and the rate and causes of mortality of released hares were investigated using a radio-telemetry technique during one study year in the vicinity of Maciejowice, Poland. Territorial ranges of released hares were between 0.14 km² and 2.86 km². The average home ranges of males were significantly greater than that of females: 1.3 km² and 0.5 km², respectively. Released hares travelled, on average, a distance of 2.6 km (range = 1.4–4.9 km per year). The annual mortality of the studied was ca. 72% and was highest in the first month after release, i.e. in December. The average lifespan of killed hares was 31 days for females and about 80 days for males. The major cause of hare mortality was predation.

Preliminary results on the ecology of raccoon in Poland are presented. The use of space (by radiotelemetry), diet composition and parasite infections (both by scat analysis) were investigated. The home-range size of the raccoon in western Poland averaged 1 km² in suburban areas (n = 5 individuals), 10 km² in the Warta Mouth National Park wetland area (n = 5), and 60 km² for a single individual studied inhabiting woodlands. Space use patterns in relation to habitat type were also studied. About 44% of the biomass consumed by raccoons were mammals, 41% other vertebrates, 12% invertebrates, 2% plant material and only 1% eggs. Three species and one genus of helminths, e.g. the humans pathogen parasite, Baylisascads procyonis, were identified.

Using questionnaires completed by 284 national park field workers I evaluated the occurrence and population dynamics of large mammals from 1996 to 2005 in all 23 Polish national parks. A total of 29 species were found: 15 carnivores, 8 even-toed ungulates, 2 lagomorphs and 4 large rodents. The greatest population growth was seen in the beaver Castor fiber, the red fox Vulpes vulpes, and three non-native species (American mink Mustela vison, racccoon Procyon lotor and fallow deer Dama dama) while the greatest population decline occurred in two other non-native species (muskrat Ondatra zibethicus and mouflon Ovis orientalis musimon) and to a lesser degree in the native brown hare Lepus europaeus. The richest and most natural large mammalian fauna occurred in the Carpathian parks (Bieszczady NP, Magura NP, Tatra NP and Pieniny NP) as well as in the eastern part of the country (especially Białowieża NP and Biebrza NP), and the poorest was found in the Sudeten parks and in the west. There was a statistically significant correlation between mammal species richness and park size, longitude as well as the degree of disturbance in and around the park (negative correlation).

Remains of invertebrates, especially insects, are frequently found in carnivores' faeces. Invertebrates are generally restricted to a given area and many factors such as landuse pattern, vegetation structure or even moisture can separate different groups; thus, invertebrates can be used as bioindicators. Forty-five samples of marten and fox scats were analysed for the presence of insect species. Thirty insect species — which were expected to be found — were identified. Canonical correspondence analysis indicated that the factor ‘species’ (i.e., marten and fox) was the main factor determining invertebrate species variation. Redundancy analysis allowed us to identify invertebrate ecological groups associated with these two carnivores. Martens prefer nest-building insects as a supplementary source of food and mainly forage in meadows, whereas foxes foraged in forest with high volumes of insects as well as necrophages. Martens preferred smaller, while foxes preferred lager insects. We conclude that insects found in faeces might play an important role in understanding food and habitat relationships between sympatric predators.

The distribution of otter and American mink tracks in the Mazurian Lakeland during winter, characterised by low temperatures and thick ice cover, was used to analyse competition between the two species for access to the limited area of foraging sites. The study was carried out in February and March, 2006 and comprised 12 lakes and sections of three rivers and two canals. Tracking was conducted along a total of 98.25 km of the shoreline, which was divided into 393 study sections, 250-m-long each. Otter tracks were recorded at all the lakes and canals under study and at two rivers. Mink tracks were recorded along all the watercourses and on eleven lakes. The otter was recorded in 25.9% of the sections, whereas American mink in 28.8% of the sections. Co-occurrence of the otter and mink was observed in 8.8% of the sections. In sections with unfrozen stretches (12.3% of all the study sections), the frequency of otter and mink tracks was significantly higher than in totally frozen sections. Co-occurrence of the otter and mink was found in 28.3% of the sections with access to open water. In unfrozen sections the frequency of co-occurrence of the two species was four times higher than in totally frozen sections. Only 20% of the sections with air holes were not visited by any of the two species. The study showed that during periods of low temperatures, when accessibility to open water and aquatic prey was limited, both species clearly preferred those parts of the water bodies where unfrozen places remained. A high rate of co-occurrence of the two species in such places indicates mutual tolerance between the otter and mink in the sections offering aquatic food resources.

Distribution data on beaver populations thriving in central Poland are common. We modelled beaver population viability to assess the current status and threats to the beaver in the 135-km-long section of the Vistula valley. We simulated different densities of expanding beaver populations and evaluated the three most significant scenarios of potential developments in the valley with the LARCH habitat model. The model output indicated higher vulnerability of low density populations to the same environmental changes. At present, suitable habitats sustain a large minimum viable population as part of one sustainable network. Hypothetical construction of two dams and removal of riparian forests within dykes would lead toa 25% reduction in population size. In contrast, river renaturalisation would increase beaver numbers by 42%. Based on the population trends we conclude that scenario analysis is beneficial in helping to evaluate future management decisions.

The abundance of wolves in Lithuania is important for the conservation of the species in the Baltic region especially for ensuring its long-term viability. On the basis of distribution maps for 2000–2005, and minimum population counts, I propose that the wolf population in the country is stable, around 200 individuals (15–20 packs). Main threats are highways and, possibly, human disturbance in fragmented forest areas, while the impact of hunting is minor. Preparation and adoption of the national species management plan and agreement on minimum viable population numbers, as well as mitigation of conflicts caused by depredation of domestic animals are the main tasks for the conservation of this species in the near future. High ecological plasticity of the wolf makes it likely that its existence in Lithuania is not threatened.

The research was conducted on 600 (311 male and 289 female) European bison skulls of the Lowland line collected between 1967 and 2006. The specimens came from the bison breeding centre in Białowieza (n = 67) and from the free-ranging population of the Polish part of the Białowieza Forest (n = 533). Two indices best differentiating male and female skulls were selected: one being the quotient of the orbital breadth EctEct and the length of the splanchnocranium StP, the second being the quotient of the neurocranium length BSt and the basal skull length BP. Using these indices we constructed an equation which produced negative values for females and positive values for males; 223 (74%) of the male skulls produced positive values consistent with sex, and 82 (26%) produced negative values, indicating female features. Those features were present mainly in skulls of young males (< 4 years old). 230 (80%) of the female skulls had shapes typical of the female sex, whereas 59 (20%) displayed male features.

The material consisted of 300 skulls (150 male and 150 female) of adult European bison from the Lowland line aged 5 to 27 years. The specimens belong to the museum collection of the Mammal Research Institute of the Polish Academy of Sciences in Białowieża. On each skull three standard measurements (BP, EctEct, SmSm) were taken. The results were standardized separately for males and females. The sum of three normalized parameters describing each skull was treated as its standardised dimension and then Perkal's natural similarity coefficients were calculated. In adult males a remarkable polarization of skull shapes was observed. In one set of the male specimens the type of a long skull with a broad forehead and narrow face was predominant (27%). In another, opposite and almost equally numerous (24%) set of male specimens, the type of a short skull with a narrow forehead and broad face prevailed. Such a polarization was not found in adult females: the type of a long skull with a narrow forehead and narrow face dominated (28% of the examined material); the remaining variants were evenly distributed.

European bison Bison bonasus refuges in the Bieszczady Mountains were characterised using four habitat variables: elevation above sea level, slope exposure, tree crown closure, and stand composition. We compared habitat composition of ranges representing a 95% probability of bison use with ranges representing a 25% probability of bison use, on a seasonal basis (summer, winter). During the growing season (“summer”), the 25% probability ranges contained more high elevation (550–749 m), other than northern-exposure areas with more open-canopied, fir-dominated forest than did the 95% probability ranges. During winter, the 95% probability ranges contained less high elevation (550–749 m), northerly exposure areas with more close-canopied, beech-fir, alder, and Scotch pine forests.

The aim of this study was to analyze the system of arteries in the brain of the giraffe, including the arterial circle of the brain, its branches and junctions, as well as individual variation of the vessels. Analyses were performed on postmortem material of 12 heads of giraffes obtained from Polish zoological gardens. The age of the examined animals ranged from 1.5 to 12 years. Moreover, arteries of one fetus aged approximately 10 months were also analyzed. Arteries of the heads were injected with latex and vinyl superchloride dissolved in acetone. In the giraffe, similarly as in other ruminant species, obliteration of the intracranial segment of the internal carotid artery was observed, together with the presence in the cranial cavity of the rostral epidural rete mirabile, from which the preserved intracranial segment of the internal carotid artery exteriorizes. The rostral cerebral artery of the brain and the caudal communicating artery, participating in the formation of the arterial circle of the brain, are formed by segments of the terminal intracranial part of the internal carotid artery. In the giraffe branches of the arterial circle of the brain included: the internal ethmoidal artery, the middle cerebral artery, the rostral choroid artery, the caudal cerebral artery, the rostral cerebellar artery and the caudal cerebellar artery. It was shown that the basilar artery was thin and could not participate in the blood supply for the brain. On the basis of the conducted analysis it was found that in the giraffe the arterial circle of the brain is supplied with blood mainly by the maxillary artery.

In recently deglaciated areas, studies of mtDNA haplotype diversity have often revealed clear phylogeographic structure for many animal species. Here, we assessed mitochondrial DNA variation of the moose, Alces alces, in northeastern Poland. Altogether, four haplotypes were found among 45 moose and the haplotype (h) and nucleotide (π) diversity estimates were 0.38 and 0.8%, respectively. The most common haplotype, H1 found in the Biebrza valley, NE Poland was exclusively present in this area and was divergent from the remaining mtDNA haplotypes in the European moose lineage. Our results indicate that the moose population in the Biebrza valley experienced severe bottleneck and could be regarded as a relic group of moose that is very distinct from others in Europe. We also found evidence for population admixture due to immigration, both, in the Biebrza valley and in Poland, in general.